The present invention is directed to a method for conditioning a metering blade, and more particularly, to a method for conditioning a metering blade using a solution of abrasive particles.
In order to manufacture coated papers, a paper substrate is typically provided, and a coating is then deposited, in a liquid state, onto the substrate. The coated substrate is then passed underneath a doctor or blade or series of doctors or blades which remove extraneous coating material from the coated substrate and smooth, spread and distribute the coating on the substrate. The coated substrate is then dried or cured, and may then be wound around a take-up reel and shipped to a customer for further processing.
When the coated substrate passes underneath the blades, the blades may create a series of visible lines on the coating in the machine direction. In particular, when debris from the paper manufacturing or coating process is captured between the nip of the blade and the coated substrate, the debris can cause such lines (known as xe2x80x9cblade linesxe2x80x9d) or other defects on the coated substrate. Furthermore, when new blades are used in the coating process, the blades may not be precisely calibrated or shaped which can also cause blade lines to be formed on the coated substrate.
Blade lines have attempted to be eliminated by changing the formulation of the coating. For example, the coating may be diluted to ensure that the coating is still in a fluid state and has not yet begun to harden when the coated substrate passes underneath the blades. However, diluting the coating may increase manufacturing time (due to the increased time required to cure the coating) and may increase the roughness of the paper coating.
Accordingly, there is a need for a method for conditioning a metering blade to reduce the presence of coating blade lines.
The present invention is a method for conditioning a metering blade through the use of abrasive particles or an abrasive solution to reduce the presence of coating blade lines. In one embodiment, the invention is a method for conditioning a metering blade of a paper coating machine. The method includes the steps of providing a paper coating machine having at least one metering blade and passing a movable substrate through the paper coating machine such that the metering blade contacts the substrate to distribute any coatings applied to the substrate. The method further includes the step of applying a solution of abrasive material to the substrate at a location upstream of the metering blade such that the abrasive material engages and conditions the blade. Other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings.